A group of state attorney generals are preparing a letter warning file-sharing companies that they could be targets of legal action if they don't take stronger action on privacy and intellectual property violations.

The letter, which a source familiar with the process said would likely be ready Thursday, follows several months of discussion between the states' top law enforcers and companies themselves. A draft letter circulated last spring was similarly critical of the file-sharing companies, but was put on hold after a draft was leaked, and the companies themselves called for dialogue.

The source said the new letter would call on the companies to be "responsible corporate citizens," asking them to do more to protect consumers from privacy invasions and identity theft, to ensure that the technology is not used to hinder law enforcement, and to discourage copyright violations.